Substituted hepta-and penta-methinecyanines



Patented Oct. 4, 1938 UNITED STATES PATENT OFFICE SUBSTITUTED HEPTA- AND PENTA-METH- INECYANINES I Walter Dieterle, Dessau-Ziebigk, and Walter Zeh, Dessau,

Germany,

assignors to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York No Drawingu Application September 12, 1933,

Serial No. 689,122. In Germany September 14,

polymethine series. 1 I

Oneof its objects are the hereinafter described Ourl'present, invention relates to; dyes of the dyes of the polymethin series which are .valuable h sensitiz'ers for photographic emulsions.

Further objects willbe seen from the detailed specificationjfollowing hereafter. V i

It isalready known to' sensitize silver halide emulsions, by means of trimethinecyanines which are substituted in the benzene nucleus. These dyes when suitably selecting the substituents distinguishbver the non-substituted dyesby an iricreased sensitizing power.

This invention is based on the discovery that g the penta-methinecyanines and hepta-methinecyanines symmetrically disub-stituted in the para- Dosi-tionsfto the; carbon atomsjcommon to the benzene ring and the heterocyclic ring have a superior sensitizing effect on silver halide emulsions than have emulsions sensitized by penta-- or'hepta-rnethinecyanines which are not substituted or substituted onlyin the 5 and 5' positions or Band 6 positions respectively.

"The dyestufissuitable for the purpose of this invention correspond with the general formula" 12.1 andfRz stand for alkyl,

7 a xy, lkyltmo, I 'alkylseleno; aryl aryl 1 I v x stands for 01, Br, J, 304C113;

"suitable acid radical,"

1!; stands for 2 and 3. p

The hydrogen atom .of the central carbon atom and/or of. the lateral carbon atoms of the polymethenyl chain can be substituted byan alkyl C104 or another group. Instead of two alkoxy groups for the substitution inthe 5 and 6 positions,;and 5" and 6' positions respectively there may be introduced a dioxymethylene group or a dioxyethylene group; in theLSa/mefmanner two aryloxy groups may be replaced by a dioXyphenylene roup. i

1 Claim. (01. 260240) The dyes are obtainable according to the desired solubility inform of the bromide, iodide, perchlorate etc. A silver halide emulsion is sensitized by incorporation of the dyes. Thus, a solution of the dye in a suitable solvent may be added to an emulsion ready for being cast, or a finished silver halide emulsion layermay be bathed in a solution of the-dye. V The dyes are made according to kno methods. The pentamethinecyanines are obtained by condensing the quaternary ammonium salt of a heterocyclic base disubstituted in the para positions to the carbon atoms common to The following examples serve to illustrate our.

invention.

Example ,1 -The dye blS-[3-8thY1r5fi-dlfl1fit oxy 'benzthiazole (2)] pentamethinecyanine iodide corresponding with the formula CB/E[B\L 52115 is obtainable by boiling for about /2 hour a mixture of 2' grams of 2-methyl-5.6-dimethoxybenzothiazole ethiodide, 1 gram of ,3-ethoXyacroleinacetal and 5 cc. of pyridine. On the addition of 10 cc. of water the dye is precipitated from the dark green solution in form of green crystals. v

The alcoholic solution of the dye has an absorption maximum at a wave length of about 685 Incorporated in a silver bromide emulsion containingabout 1 per cent of silver iodide the dye imparts to it a range of sensitivity from about 600 to 830 with a maximum at a Wave length of about 745,LL[L.

Example 2.The dye bis- [3-ethyl-5-ethoxy- G-methyl-benzthiazole- (2) l-pentamethine cya nine iodide corresponding with the formula H30 s s lHHHHHll 2 02 11:. I (EzHt is obtained when Working according to the method described in the preceding example but starting from the 2.6-dimethyl-S-ethoxybenzothiazole. The dye crystallizes from alcohol in bright green crystals.

The alcoholic solution of the dye has an absorption maximum at a wave length of about 675 Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 600; to 810 m with a maximum at a wave length of about 735 Example 3.The dye bis-[3-ethyl-5.6-dimethoxy-benzthiazole- (2) l-heptamethinecyanine iodide corresponding with the formula may be obtained by dissolving 2 grams of 2- methyl-5.6-dimethoxybenzothiazole ethiodide and 1 gram of e-phenylimido-e-phenylamido-ax pentadiene-hydrobromide in 10 cc. of hot alcohol and this mixture is boiled for about 10 minutes with the addition of 0.5 cc. of diethylamin. The dye separates in form of green crystals.

Incorporated in a silver bromide emulsion con- S I'HHHHHHH 2 taining about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 600 to 930 with a maximum at a Wave length of about 845 Example 4.When working as described in the preceding example, but starting from the 2- is obtained by boiling 2 grams of 2-methyl-5.6-

diethoxy-benzoselenazole ethiodide in 10 cc. of alcohol with 1 gram of e (n-methyl-phenylimino) a-(n-methyl-phenylimino)-a.- pentadiene hydrobromide, adding 1 cc. of an alcoholic solution of trimethylamine of 50 per cent strength and continuing boiling until the dye begins to separate. The dye which has been precipitated by cooling is recrystallized from methanol and forms then blackish green little rods.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 650 to 950/141. with a maximum at a wave length of about 865/L/L.

Example 6.The dye bis-[3-ethyl-5.6-dimethoxy-benzthiazole- (2) l-v-methyl-penta-methine cyanine iodide corresponding with the formula H3oo- -s s -0021:

l'lillilgHsl-illgg s 2 H300 4 g qg g jg/W OOH: (Dz H5 I (ma may be obtained by heating 2 grams of Z-methyl- 5.6-dimethoxybenzothiazole ethiodide in cc. of pyridine with 1 gram of fi-ethoxyamethylacroleinacetal for about 30 minutes to 130 C. On the addition of about 10 cc. of water the dye separates in form of bluish green flakes. The dye crystallizes from alcohol in green felted needles.

The alcoholic solution of the dye has an absorption maximum at a wave length of about 685 Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 600 to 830M, with a maximum at a wave length 0f about 745/14! Example 7 .--The dye bis-[3-ethyl-5.fi diethoxy-v benzthiazole (2) l- 6 -methyl heptamethinecyanine iodide corresponding with the formula mono- 7 may be obtained by boiling 2 grams of Z-methyl- 5.6-diethoxy-benzothiazole ethiodide with 1 gram of E-phenylimido or phenylamido-' -methyl-ax pentadiene hydrobromide until the mixture becomes green. After cooling the dye separates in form of green crystals.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 600 to 930M, with a maximum at a wave length of about 845/141 Example 8.The dye bis-[3-ethyl-5.6-dimethyl benzselenazole (2) l 6 methyl-heptamethinecyanine iodide corresponding with the may be obtained when working according to the preceding example, but startingfrom the 2.5.6- trimethylbenzoselenazole ethiodide. The dye crystallizes from alcohol in light green crystals.

Incorporated in a silver bromide emulsion containing about 1 per cent of silver iodide the dye imparts to it a range of sensitivity from about 700 to 910,!!- with a maximum at a wave length Of about 850/L/L- What we claim is: 1

Bis- [3-ethyl 5.6 diethoxy-benzthiazole-(2) heptamethinecyanine iodide.

WALTER DIE'I'ERLE. WALTER ZEH. 

